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<head>
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    <title>Document</title>
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<body>
    <!-- Array,Object,Function -->
    <script>
        /* 1.声明数组 */
        var arr =["html","css","javascript"];
        /* shift+alt+a 多行注释 */
        
        /* 2.读取数组中的值 通过下标去读取 */
        console.log(arr[0])
        console.log(arr[2])
        /* 3.length  通过这个属性可以获取数组的长度 */
        var length = arr.length;
        console.log(length);
        /* 4.读取数组最后一个元素的值 */
        var  lastChild = arr[arr.length-1];
        console.log(lastChild)
    </script>
</body>
</html>